The role of surface chemical reactivity in the stability of electronic nanodevices based on two-dimensional materials "beyond graphene" and topological insulators

Here, we examine the influence of surface chemical reactivity toward ambient gases on the performance of nanodevices based on two-dimensional materials "beyond graphene" and novel topological phases of matter. While surface oxidation in ambient conditions was observed for silicene and phosphorene with subsequent reduction of the mobility of charge carriers, nanodevices with active channels of indium selenide, bismuth chalcogenides and transition-metal dichalcogenides are stable in air. However, air-exposed indium selenide suffers of p-type doping due to water decomposition on Se vacancies, whereas the low mobility of charge carriers in transition-metal dichalcogenides increases the response time of nanodevices. Conversely, bismuth chalcogenides require a control of crystalline quality, which could represent a serious hurdle for up scaling

Study on the morphological evolution of bud break in Vitis vinifera L.

The aims are to evaluate morpho-anatomical bud development during dormancy and to compare the heat requirement needed to start bud break in several grapevine cultivars characterised by different geographic origins. A detailed description is presented of the bud growth stages of Vitis vinifera cultivars to contribute to the standardisation of national and international testing systems of fruit growing. Based on the general BBCH-scale, the codes describe the first stages of budbreak in several cultivars with different geographical origins. Dormancy release was evaluated both under natural and forcing conditions, appropriate method to establish the budbreak of deciduous species. The cultivars were characterised in relation to the achievement of complete bud scale opening stage (03 of BBCH scale) which is suggested to consider as an early and indicator of budbreak.

Evaluation of the effect of esca disease on bud break in Vitis vinifera L.: Possible relationship between cultivars and rootstocks

The aim of this study was to investigate the effect of esca disease on bud break of grapevine in relation to different rootstock combinations. For this purpose under field conditions observations of flower bud phenological stages were carried out on three widespread grapevine cultivars 'Cabernet Sauvignon', 'Sangiovese' and 'Trebbiano toscano'. Further phenological observations were recorded under forcing conditions using 'Cabernet Sauvignon' as the most susceptible to esca disease. Each cultivar was grafted on K5BB, 1103P and own rooted. The plants were infected by esca due to the natural presence of fungi in the vineyard. Results showed that esca disease significantly delayed bud break of symptomatic vines for several years. Grapevines on different rootstocks showed different bud break changes, in particular those on K5BB were the most susceptible to esca.

Evaluation of the effect of esca disease on bud break in Vitis vinifera L.: possible relationship between cultivars and rootstocks

The aim of this study was to investigate the effect of esca disease on bud break of grapevine in relation to different rootstock combinations. For this purpose under field conditions observations of flower bud phenological stages were carried out on three widespread grapevine cultivars 'Cabernet Sauvignon', 'Sangiovese' and 'Trebbiano toscano'. Further phenological observations were recorded under forcing conditions using 'Cabernet Sauvignon' as the most susceptible to esca disease. Each cultivar was grafted on K5BB, 1103P and own rooted. The plants were infected by esca due to the natural presence of fungi in the vineyard. Results showed that esca disease significantly delayed bud break of symptomatic vines for several years. Grapevines on different rootstocks showed different bud break changes, in particular those on K5BB were the most susceptible to esca

Phase-sensitive terahertz imaging using room-temperature near-field nanodetectors

Imaging applications in the terahertz (THz) frequency range are severely restricted by diffraction. Near-field scanning probe microscopy is commonly employed to enable mapping of the THz electromagnetic fields with sub-wavelength spatial resolution, allowing intriguing scientific phenomena to be explored, such as charge carrier dynamics in nanostructures and THz plasmon-polaritons in novel 2D materials and devices. High-resolution THz imaging, so far, has relied predominantly on THz detection techniques that require either an ultrafast laser or a cryogenically cooled THz detector. Here, we demonstrate coherent near-field imaging in the THz frequency range using a room-temperature nanodetector embedded in the aperture of a near-field probe, and an interferometric optical setup driven by a THz quantum cascade laser. By performing phase-sensitive imaging of strongly confined THz fields created by plasmonic focusing, we demonstrate the potential of our novel architecture for high-sensitivity coherent THz imaging with sub-wavelength spatial resolution. (c) 2018 Optical Society of America under the terms of the OSA Open Access Publishing Agreemen

Broad N2H+ emission towards the protostellar shock L1157-B1

We present the first detection of N2H+ towards a low-mass protostellar outflow, namely the L1157-B1 shock, at about 0.1 pc from the protostellar cocoon. The detection was obtained with the IRAM 30-m antenna. We observed emission at 93 GHz due to the J = 1-0 hyperfine lines. The analysis of the emission coupled with the HIFI CHESS multiline CO observations leads to the conclusion that the observed N2H+(1-0) line originates from the dense (> 10^5 cm-3) gas associated with the large (20-25 arcsec) cavities opened by the protostellar wind. We find a N2H+ column density of few 10^12 cm-2 corresponding to an abundance of (2-8) 10^-9. The N2H+ abundance can be matched by a model of quiescent gas evolved for more than 10^4 yr, i.e. for more than the shock kinematical age (about 2000 yr). Modelling of C-shocks confirms that the abundance of N2H+ is not increased by the passage of the shock. In summary, N2H+ is a fossil record of the pre-shock gas, formed when the density of the gas was around 10^4 cm-3, and then further compressed and accelerated by the shock.Comment: ApJ, in pres

Esca symptoms appearance in Vitis vinifera L.: influence of climate, pedo-climatic conditions and rootstock/cultivar combination

This study investigated the appearance of esca symptoms in relation to environmental factors and the rootstock/cultivar combination in an experimental setting between 2004 and 2009. Among the common genotypes showing susceptibility to the esca disease, four cultivars were considered: ‘Cabernet Sauvignon’, ‘Sangiovese’, ‘Trebbiano Toscano’ and ‘Chardonnay’. These cultivars were studied own-rooted and in combination with two rootstocks: Kober 5BB and 1103 Paulsen. The difference in susceptibility of cultivars to esca appeared negatively related to the graft. No clear relation was found between esca appearance and environmental factors. Moreover, an unexpected discordance between esca incidence percentage and mortality rate was observed